Eco-friendly preparation of superhydrophobic copper surfaces for oil/water separation

摘要

Copper surfaces decorated with micro- and nanostructures can be applied to self-cleaning superhydrophobic surfaces, energy devices and pollution remediation. Wet chemical etching is the classical strategy to grow micro- and nanostructures on copper surfaces. However, such processes usually produce hazardous chemical waste. Here, we present a one-step, eco-friendly and solvent-less alternative to conventional wet chemical methods. Our method involves the use of volatile compounds released from yolk and egg white of boiled chicken eggs as green oxidants for the growth of micro- and nanostructures on the copper surface. After treatment with egg components, copper substrates were modified with stearic acid to make them superhydrophobic. Stearic acid-coated substrates had a contact angle of about 150 degrees, thus confirming their superhydrophobicity. Similar to copper sheets, superhydrophobic copper meshes were also prepared and used for the selective removal of oil from oil/water mixture. Results show that our method produces a wide range of shapes including hollow and solid spheres, nanoflakes, nanoneedles and dome shapes. We found that H2S, the major volatile compound emitted by eggs, is mainly responsible for the growth of microstructures. Therefore, our method can be used both to capture H2S and to design specific surfaces. The mesh exhibited excellent separation efficiency, more than 95% for the organic solvents. A key advantage of our method is that it can be performed also using waste and expired eggs.